Process and system for drying and heat treating materials

ABSTRACT

This invention discloses systems and methods for conversion of high moisture waste materials to dry or low moisture products for recycle or reuse. The equipment systems comprise a gas turbine generator unit (preferred heat source), a dryer vessel and a processing unit, wherein the connection between the gas turbine and the dryer vessel directs substantially all the gas turbine exhaust into the dryer vessel and substantially precludes the introduction of air into the dryer vessel and wherein the processing unit forms the dried material from the dryer vessel into granules, pellets or other desired form for the final product. Optionally, the systems and methods further provide for processing ventilation air from manufacturing facilities to reduce emissions therefrom.

FIELD OF THE INVENTION

This invention relates to processes, systems and equipment foreconomically converting waste, intermediate or raw materials, eitherorganic or inorganic in nature, into products useful as animal or humanfood, fuel products, recyclable materials for further or new processing,fertilizer or soil builder products, materials for disposal at reducedvolumes and final products for market.

BACKGROUND OF THE INVENTION

Industrial processing facilities for food, paper, drug and othermanufacturing, processing and packaging are becoming larger and moreconcentrated. Consequently, the waste streams produced by thesefacilities are becoming increasingly larger, more concentrated locallyand more difficult and costly to dispose of due to governmentregulations as well as decreasing numbers and sizes of landfill sitesthat are available for waste disposal. More people are consumingcommercially prepared and processed food both in and out of the homethan ever before. This is true not only in the United States, but inother countries as well. This phenomenon creates an enormous amount ofwaste, i.e., food scraps, over-ripe food, trimmings, spoilage and animalparts discarded during food preparation, that is concentrated in largeprocessing facilities and that must be disposed of in municipal sewage,landfills or incinerators. The waste is produced in larger and largeramounts in facilities that produce pre-prepared food products, such asfrozen foods, pre-prepared, ready-to-eat salad mixes, heat-and-servemeals, and the like for home, institutional, airline, hotel and otheruses. This waste is frequently difficult and costly to dispose of,primarily because it commonly has high water content and has littleeconomic value as a fuel. The art is replete with various complexprocesses and systems that address the problems of such waste disposaland/or conversion to useful, recyclable or disposable products. However,most prior processes and systems are not practical or desirable due toeconomic considerations, due to the limited type of waste that can betreated or processed in a particular system, due to environmentalproblems caused by operation of the processes or system or due to otherdisadvantages. Moreover, the eruption of transmittable spongiformencephalopathy (TSE), particularly bovine spongiform encephalopathy(BSE) and scrapie diseases, has made inactivation of pathogenic agentsessential, whether the waste material is processed for recycle or fordisposal. Animal wastes, such as offal, paunch waste material andcarcasses, are subject to carrying infectious agents including fungi,bacteria, viruses and prions associated with BSE, TSE, etc. The priorart processes available are either not satisfactorily effective from atechnical standpoint or are not economically desirable. A need thereforeexists for methods of processing and/or disposal of food processing,slaughter house, and similar wastes without the technical or economicdisadvantages of the prior art.

Examples of the prior art publications that have addressed the aboveproblems by digestion, incineration, volume reduction and/ordecomposition include U.S. Pat. No. 5,685,153 to Dickinson et al.; U.S.Pat. No. 6,197,081 to Schmidt; U.S. Pat. No.6,506,311 to DeGarmo et al.;U.S. Pat. No. 6,534,105 to Kartchner; U.S. Pat. No. 6,638,757 to Teranet al.; U.S. Pat. No. 6,716,360 to Titmas; U.S. patent applications2002/0122850 by Kartchner, 2003/0098227 by Okamoto et al. and2004/0055716 by Landalv et al., the disclosures of which areincorporated herein by reference in their entirety.

Another problem existing in waste treatment and disposal operations isair pollution, including greenhouse gas emissions, including methane andCO₂, and emission of gases having noxious odors, such as slaughterhouseand rendering plant operations. As residential housing areas haveexpanded, many have encroached on land adjacent to various foodprocessing and other industrial operations, and complaints fromresidents regarding the noxious odors escalate. The prior art hasoffered little to satisfactorily and economically address the problemsof controlling and preventing noxious odors from industrialmanufacturing facilities and waste disposal facilities.

There is also a general problem of removal of water from high watercontent, dilute process streams, whether it is a waste stream, finalproduct stream or an intermediate process stream. The removal of waterfrom process streams having a high water content is costly, energyintensive and time consuming.

It is apparent from the above that there is a substantial unmet need forenvironmentally and economically acceptable technologies for disposal ofvarious waste materials, for control of noxious and greenhouse gases,for conversion of wastes into useful or recyclable products and forefficient and economical removal of water from high water contentprocess streams. The present invention is directed to methods,apparatus, systems and products for meeting some or all of these needs.

SUMMARY OF THE INVENTION

The present invention provides economical and simplified methods,systems and apparatus for converting organic and inorganic wastematerials into products that are useful as animal feed, fuels,recyclable materials for processing and other uses. The presentinvention further provides economical and simplified methods, systemsand apparatus for controlling and containing noxious, odoriferous andgreenhouse gases from various industrial and waste treatment operations.

In one aspect, this invention provides a method for processing a wastematerial feedstock comprising operating a gas turbine generator toproduce electricity and exhaust gases; contacting the exhaust gases withthe waste material feedstock having a moisture content of at least about30% by weight in a dryer vessel for a contact time sufficient toproduce, without significant oxidation of the waste material feedstock,a dried material having a moisture content less than about 20% byweight; and optionally provides for processing and forming the driedmaterial into a granular, pellet or prill product form suitable forconventional handling and transport.

In another aspect, this invention provides a method for processing awaste material feedstock comprising operating a gas turbine generator toproduce electricity and exhaust gases having a temperature greater than1,000° F.; contacting the exhaust gases having a temperature greaterthan 1,000° F. with waste material feedstock having a moisture contentof at least about 30% by weight in a dryer vessel for a contact timesufficient to produce a dried material having a moisture content of lessthan about 20% by weight, and optionally provides for granulating,pelletizing or prilling the dried material into a product form suitablefor conventional handling and transport. Optionally, the contact of theexhaust gases and the waste material feedstock is conducted withoutsignificant oxidation of the waste material feedstock.

In another aspect, this invention provides apparatus for drying and/orconverting waste material feedstock comprising a gas turbine incombination with a dryer vessel adapted for receiving waste materialfeedstock and for receiving the exhaust gases from the gas turbinethrough a connection; wherein the connection between the gas turbine andthe dryer vessel is adapted to substantially preclude the introductionof air into the dryer vessel and optionally provides the dryer vesseladapted for such drying and/or converting the waste material feedstockby direct contact of the exhaust gases and the waste material feedstock.

In another aspect, this invention provides a portable system forprocessing waste material feedstock comprising at least one portabledryer unit adapted for drying or heat treating a waste materialfeedstock to produce a dried or altered material and at least oneportable processing unit adapted for converting the dried or alteredmaterial from the dryer unit into a product having a form suitable forconventional handling and transport, and optionally further providessuch a portable system wherein the dryer unit comprises a gas turbineand a dryer vessel. Further, the invention optionally provides such aportable system wherein the gas turbine and dryer vessel are connectedby an arrangement adapted to pass the gas turbine exhaust gases into thedryer vessel and to preclude the introduction of air into the dryervessel.

In another aspect, this invention provides the above portable systemcomprising a first skid-mounted unit comprising the gas turbinegenerator adapted for producing electricity; and a second skid-mountedunit comprising the dryer vessel adapted for connection to the gasturbine to receive the gas turbine exhaust gases and to preclude theintroduction of air into the dryer vessel. Optionally a thirdskid-mounted unit is provided comprising the processing unit. Preferablythe portable systems of this invention comprise rail-mounted,truck-mounted or semitrailer-mounted units. In another aspect, thisinvention provides the portable system, comprising the gas turbine anddryer vessel, plus an optional processing unit, configured and sized fora single skid-mount or truck-mount installation. Another optional aspectcomprises an enclosure or enclosures for the portable units, primarilyfor operating noise attenuation as well as protection from weatherconditions.

In another aspect, this invention provides a product comprising a wastematerial feedstock thermally treated at sufficient temperatures andwithout significant oxidation for a sufficient period of time to destroyor convert to acceptable forms substantially all undesired componentspresent in the waste material feedstock, which comprise undesiredorganisms, microorganisms, pesticides, antibiotics, hormones, prions orviruses. Preferably the product contains less than detectable levels ofeach such undesired component not so destroyed or converted, andoptionally further provides such thermally treated material in the formof a product suitable for conventional handling and transport. Thisinvention further provides a product comprising thermally treated wastematerial feedstock which contains NO_(x), SO_(x) or CO_(x) componentsabsorbed or complexed therein as a result of contact of the wastematerial feedstock with gas turbine exhaust gases in a confined space inthe absence of significant oxidation of the waste material feedstock.

In another aspect, this invention provides a dried or altered materialor product comprising a waste material feedstock thermally treated atsufficient temperatures without significant oxidation and for sufficientperiod of time to provide a self-binding product suitable forconventional handling and transport.

In another aspect, this invention provides a system for processinggreenhouse gases and noxious or odoriferous gases from waste materialfeedstock and/or such gases emitted by the facility producing a wastematerial feedstock comprising a gas turbine having a combustion airintake and a facility having ventilation air exhausted from thefacility, wherein the combustion air intake is adapted to receive atleast a portion of, and preferably substantially all of, the ventilationair exhausted from the facility. The gas turbine can optionally comprisea gas turbine generator and can optionally include a dryer vesseladapted for receiving the gas turbine exhaust and for receiving and heattreating waste material feedstock. In an alternative aspect, thisinvention provides said systems for processing manufacturing gases andnoxious or odoriferous odors or gases through the combustion air intakeof a reciprocating engine, which can optionally include an electricgenerator and can optionally include a dryer vessel adapted forreceiving the engine exhaust.

In another aspect, this invention provides apparatus for treating wastematerial feedstock comprising a gas turbine having a combustion airintake adapted to receive ventilation air from a facility producingwaste material feedstock, a dryer vessel having a connection adapted forreceiving exhaust gases from the gas turbine and having an inlet forreceiving waste material feedstock. Optionally the combustion air intakecan be adapted for connection to the facility ventilation system wherebythe combustion air intake receives substantially all the ventilation airexhausted from the facility. Additionally in this aspect, the connectionbetween the dryer vessel and the gas turbine exhaust can be adapted tosubstantially preclude the introduction of air into the dryer vessel.

The above aspects and other aspects will be apparent to one skilled inthe art from the disclosure herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a process for treating waste materialfeedstock using the process and equipment in accordance with the presentinvention.

FIG. 2 is a plan view of the process units according to this inventionin the form of portable skid-mounted, truckable units.

FIG. 3 is a plan view of the process units according to this inventionin the form of portable skid-mounted, truckable units in anotherconfiguration.

FIG. 4A is a plan view and FIG. 4B is an elevation view of anillustration of a configuration of the system of this invention mountedon a semitrailer truck.

FIG. 5 is a schematic of processes for preventing emission ofgreenhouse, noxious odors and other gases to the atmosphere using thesystems of the present invention.

DESCRIPTION OF THE INVENTION

This invention provides an economical, efficient and simplified solutionto the increasingly severe problem of environmental pollution caused bywaste material and gases from industrial operations. Prior art methodsand systems provided to date either are not sufficiently effective inconversion of such waste material and gases to a safe, environmentallyacceptable form or are not adaptable to be economically feasible forsmall as well as large commercial operations. Other problems exist withmany of the prior art systems, including uneconomical to operate,failure to decontaminate and failure to prevent air pollution (or infact causing additional environmental problems in the operation of theprocess).

Examples of the prior systems and their deficiencies include thefollowing. Digestion processes, whether aerobic or anaerobic, are slow,inefficient and produce a sludge that must be disposed of, typically ina landfill. Digestion or composting systems designed to produce biogas,typically methane, for fuel do not provide economically beneficialproduction of fuel and are costly to operate, because the fuel producedis not produced at a sufficient rate, is not of sufficient thermal valuefor economic operation, is a “dirty” fuel in that it producesenvironmentally unacceptable emissions when burned and/or is difficultto burn efficiently due to its variable content. This variable andinconsistent content of contaminants and fuel value can actually damagesome systems, such as gas turbines, due to corrosion or uncontrollable,unpredictable burning conditions. Digestion and composting systemsdesigned to produce a usable sludge have the drawback that such sludgeproducts produced are not usually free of biologic or chemicalcontaminants that are undesirable or prohibited for use or disposal,such as on crop land. Consequently, biogas production operations producea depleted sludge that is costly to dispose of in an environmentallyacceptable way, which is frequently in a landfill operation qualified totake such sludge.

Treatment systems that employ heat and chemical treatment areinefficient and frequently ineffective in producing a safe finalproduct. These include pH adjustment and chemical additives, usuallywith heating to help kill organisms present. Some heat treatment systemsemploy pressure (for higher temperature cooking), microwave heating,radiation and other supplemental treatments, which only serve to add tothe cost of operation with diminishing benefit in product quality orenvironmental cleanup. In many cases the additional complexity oftreatments and combinations of process steps results in more negativeenvironmental impact from the resources employed and byproducts producedthan is achieved in beneficial environmental impact from the totaltreatment. Many systems produce alternative or additional byproductsthat are contaminated or cause collateral environmental pollution intheir operation. Systems that involve incineration, partialincineration, gasification or pyrolysis are similarly inefficient andnot sufficiently effective, because incineration produces additionaleffluents that must be contained to prevent alternate or additional airpollution. Also, while incineration and pyrolysis systems produce aproduct that may be sufficiently sterilized, the product may containother undesirable byproducts of the incineration and pyrolysis such ascarcinogens, making the product unsuitable for animal feed, recycle orother desired uses, thus requiring undesirable disposal in landfill.And, incineration or partial incineration systems carry the additionalrisk of potentially uncontrollable or flash fires, which at a minimumdamages the processing equipment and at worst poses safety issues.

Prior art systems have not satisfactorily addressed the problem ofnoxious gases and greenhouse gases that are produced in industrialmanufacturing operations and in waste material treatment operations.Sources of such gases are the manufacturing processes themselves, thewaste material produced and the bioconversion or decomposition of thewaste material. These gases are typically vented or released to theatmosphere, but may be objectionable to nearby residents due to thenoxious odors and are environmentally objectionable due to theatmospheric pollution caused by the greenhouse gases contained therein.

The present invention provides new technology in the form of processes,apparatus and systems for conversion of waste material feedstocks touseful, environmentally acceptable materials and products. In addition,the present invention provides technology which reduces or eliminatesthe undesirable environmental impacts of noxious and greenhouse gasesproduced in manufacturing operations and in bioconversion of wastematerials from the manufacturing operations. One major advantage of thepresent invention resides in the aspect that, in most waste materialfeedstock processing according to this invention, all waste solids canbe optionally contained within the processes and systems and become partof the final product produced by the processes and systems of thisinvention. Thus, the present invention can completely eliminate thenecessity of disposing of any remaining sludge or other solids in alandfill by converting and/or incorporating all the waste materialfeedstock solids into the final product.

The term “waste material feedstock” is used herein to mean and includewaste matter which comprises organic matter and which comprisesinorganic matter, or mixtures thereof. Included in the organic wastematter category are: woody or cellulosic and chemical waste productsfrom agricultural operations, such as bagasse, rice hulls, straw,alfalfa, orchard and vineyard prunings, citrus pulp, corn cobs, beetpulp, hatchery waste, yard wastes, landscaping wastes, mushroom growingwastes, etc., from forestry and lumber operations, such as scrap wood,sawdust, bark, limbs, etc., from pulp and paper operations, includingKraft mill black liquor from sulfate pulping, from de-inking milloperations, from nursery operations, such as dead or diseased plants andfrom building demolition and construction; mixed plastics or automobileshredder residue (ASR); food processing wastes from processed orpre-processed food product manufacturing, such as such as frozen foods,pre-prepared, ready-to-eat salad mixes, heat-and-serve meals, cannedfoods, and food services businesses, such as restaurants, institutionalmeal providers, airline meal providers, etc.; residual meat, bones,offal, skin, poultry waste, feathers, feather meal, hair, hair meal,seafood meal, blood, blood meal, bone meal etc. from slaughter house andmeat and fish packing operations; livestock, poultry and pet carcassesfrom farms, feedlots, slaughter houses, and veterinarian clinics,including cattle, sheep, goats, hogs, horses, chickens, geese, ducks,and virtually any other animal from any source of carcasses, body parts,organs or tissues that must be disposed of; body parts, organs andtissues from medical facilities; fermentation and distillation operationwastes, such as soy sauce waste, wine and sake lees, tofu refuse, grapeskins and seeds, mash and sour mash residue, etc.; cheese makingoperations, recycle waste operations, such as paper, plastics, tires,foamed styrene, cardboard, etc. and other servicing, processing andmanufacturing operations that involve organic materials. Included in theinorganic matter category are: product streams, waste streams andmaterials from mining operations, iron and steel mill operations,foundry operations, well drilling operations, production of zinc borate,zinc oxide, magnesium oxide, silicon dioxide, titanium dioxide, aluminatrihydrate, ceramic fibers, iron oxide, gypsum, gypsum board, silica,lime, calcium carbonate and the like. Another feedstock useful in thisinvention is contaminated soil for remediation processing, e.g., soilcontaminated with hydrocarbon fuels, pesticides, nitrates and the like.As will be apparent to one skilled in the art, mixtures of organic andinorganic waste materials will be useful in this invention. Thepreferred waste material feedstock for use in this invention is thatwith a high water content, which makes that feedstock uneconomical orundesirable to treat or process by prior art methods. Large componentsof a waste material feedstock, such as prunings, building demolitionmaterials, fruit pits, tires, bones, carcasses, etc., preferably arecomminuted or shredded to particle sizes suitable for processing in thesystems and equipment selected for carrying out this invention. Thesizing may be done using any suitable equipment, such as mills, choppersor shredders. Sizing should be done in an enclosed environment to avoidaerosol pathogen emissions into the outside environment. Typically, thewaste material will have a high water content, as discussed below. Theterm “waste material feedstock” is also used herein to includeintermediate products and raw materials for further processing intoother products which are not waste products. For example, this inventioncan provide efficient processes and systems for removal of water fromprocess streams and/or provide heating to thermally convert or react aproduct stream to a converted or reacted product (in batch or continuousoperations). Other examples of the various uses of this inventioninclude drying and treating slaughterhouse waste to produce a slurriedor solid (e.g., granulated) animal feed having significant proteinand/or calcium content; processing lumber and paper manufacturing wastesor intermediate streams to produce recyclable cellulose, paper or woodmaterials or products useful in manufacture of particle board,cardboard, etc., or to produce a solid cellulose or wood product usefulas a fuel; drying and processing potato peelings and other waste frompotato processing facilities to produce an animal feed supplement or afertilizer/soil builder product; removing water from and/or converting(cooking, pasteurizing, sterilizing, etc.) process streams in human foodproduction facilities, such as production of oatmeal, corn flakes, cornsyrup, corn meal, mashed potatoes, sugar, milk, cheese, snack foods andother food products such as pet food; and removing water from and/orconverting or reacting process streams in drug, chemical and othermanufacturing facilities. As is apparent, the systems and processes ofthis invention can be used to process a feedstock by dehydration withoutconversion or reaction, by conversion or reaction without dehydration,or by any combination or proportion of both. The systems and apparatusof this invention can also be adapted for installation at particularindividual facilities to intercept the waste streams therefrom andprevent such waste streams from entering and burdening municipal sewagetreatment facilities. For example, large food processing facilities forproducing prepared meals for institutions, airlines, etc., normally dumptheir waste food materials in a municipal sewer or landfill. Wasteprocessing systems and units according to this invention can be sizedand installed at such a facility to process such waste food materials toproduce a useful product, such as an animal feed or a fertilizer/soilbuilder product which has economic value, and to reduce the burden onthe municipal sewage treatment facilities. With many municipal sewagetreatment facilities reaching full capacity and the cities being facedwith major capital expenditures to build new or expanded facilities,this invention provides an economically attractive alternative byprocessing waste streams on site at large manufacturing facilities toproduce a useful product and relieve the burden on the municipal sewagesystem. The systems of this invention can also be adapted to sanitarilytreat, on site, raw sewage, organic hazardous waste, etc., from officebuildings, hospitals, hotels, etc., to produce, on site, a fertilizer,recyclable or safe disposal product, thus further relieving the burdenon the municipal sewage system. This aspect of this invention beingdesigned for processing animal waste material and municipal sewage, isdisclosed in commonly assigned copending U.S. patent application Ser.No.______ (Attorney Docket No. 033976-004) filed on even date herewith,the disclosure of which is incorporated herein by reference in itsentirety.

The present invention provides a simplified, economically efficientalternative to the prior art which provides in its preferred aspects, a100% usable product which provides 100% conversion of waste materialfeedstock solids into useful products and which eliminates the problemunsolved by the prior art of disposal of solids left over from variouswaste material feedstock treatments. The present invention isprincipally useful, depending on the waste material feedstock to beprocessed, in processing waste materials into food products, animal feedproducts, fuel products, fertilizer or soil builder/soil supplementproducts, products suitable for efficient recycle, remanufacture, reuseor transport, and safe products suitable for environmentally acceptabledisposal. According to the present invention, the animal or plantnutrient values in the product from a waste material feedstock can bemaximized if composting, digestion, incineration and oxidation of thewaste material feedstock are avoided or at least minimized. In thisinvention, the high temperature treatment of waste material feedstock,preferably by direct contact with hot gases, e.g., >1,000° F., destroysor converts to harmless forms substantially all undesirable componentspresent in the waste material feedstock, including organisms,microorganisms (including genetically modified organisms, bacteria,pathogens and other microorganisms), seeds, pesticides, antibiotics,hormones, prions and viruses, particularly when such heat treatmenttakes place for a sufficient time and without significant oxidation,incineration or pyrolysis of the waste material feedstock. The treatmentat sufficiently high temperatures for a sufficient amount of time in theabsence of significant oxidation and/or pyrolysis “cooks” or otherwiseconverts or transforms the waste material feedstock into a self-bindingproduct, whereby it can be formed into conventional pellets, granules,prills or other forms, usually without the need for addition of bindersor other agglomerating additives, which have sufficient physicalhardness and strength to be used in conventional product handling andtransport equipment and operations. Additionally, the present inventionprocesses and systems can be adapted to produce liquid or slurryproducts that comprise waste material feedstocks (including intermediateprocess streams or intermediate products) that have been dehydrated tothe desired moisture content level and/or have been converted, reactedor altered physically and/or chemically as desired. This invention alsoprovides for recovering and recycling the water removed from the wastematerial feedstock, which water can be used for process water, livestockwater, irrigation or other industrial uses, and for recovering andrecycling all solids (fines or other) produced in the process, so thatthere are no significant solid products produced or resulting from thisinvention other than the desired products suitable for commercial use.The selection and adaptation of the processes, apparatus and systems ofthis invention to treat or process a particular feedstock to produce aparticular desired solid, liquid or slurry product for end use, recycleor disposal will be apparent to one skilled in the art from thedisclosure herein.

According to this invention, a most efficient way of providing the hotgases for contact with the waste material feedstock is the exhaust froma gas turbine, and preferably a gas turbine electric generator.According to the system of this invention, the gas turbine is fueledfrom locally available conventional fuel sources, because conventionalfuels provide the most efficient, reliable and controllable operation ofthe gas turbine. The electricity produced from the gas turbine generatoris preferably sold back into the local power grid as a revenue sourcefor the operation of this invention, but the electricity can be usedinternally in the operation of the system of this invention or in othernearby operations as a supplemental source of power or in a combinationof uses for power and heat recovery from the processes employed in thisinvention. It is preferable and more efficient in the operation of thisinvention to merely sell the electric power produced to the local powergrid. This enables varying the operation of the processes and equipmentof this invention in the most efficient and effective manner fortreatment of the waste material feedstock to produce the desired qualityand quantity of products without concern for or being constrained by anyparticular minimum or necessary level of electricity output or the needfor an unchanging level of electricity output.

One important feature of the process and apparatus of this invention isthat the gas turbine and the waste material feedstock dryer vesselreceiving the exhaust gas from the gas turbine are connected togethersuch that induction of outside air into the dryer vessel is precludedand the dryer vessel preferably receives the exhaust gases directly fromthe gas turbine. It is preferred that 100% of the gas turbine exhaustgases are passed into the dryer vessel and, for most efficientoperation, preferably without passing through any intervening heatexchanger, silencer or other equipment in order that the dryer vesselreceives the maximum heating from the gas turbine exhaust. But, it isrecognized that excess exhaust gases not needed for the dryer vesseloperation can be diverted to provide heat required in other steps in thesystems of this invention or in other nearby operations. It is alsopreferred that the exhaust gases result from conventional and efficientcombustion ratios in the gas turbine so that the exhaust gases containminimum or limited amount of free oxygen, essentially no unburned fuel,no exposed flame and that the optimum exhaust gas temperature (EGT) isachieved, for maximum heat produced, per unit of fuel consumed. Ifdesired, combustion can be at stoichiometric ratio for peak EGToperation at maximum temperature and maximum heat input for the processand system of this invention. The absence of excess oxygen in theexhaust gases, precluding outside air induction into the dryer vessel,the absence of exposed flame and operation at the temperatures set forthherein prevents significant oxidation of the waste material feedstock inthe dryer vessel, preserves the maximum nutrient value in the wastematerial feedstock for containment in the end product and, when theoutput of the dryer vessel is a dry, oxidizable material, prevents thedanger of fire damage to the equipment and provides an operation safefrom flash fires in the dryer vessel. The absence of excess fuel in theexhaust gases prevents the exhaust gases from being a source ofhydrocarbons that must be scrubbed from the vapor effluent from theoperation of this invention before being released into the atmosphere.In other preferred operations of this invention it may be desired oressential that air or oxygen be introduced in controlled quantities orratios to provide a desired oxidation or chemical conversion of thewaste material feedstock in the dryer vessel.

In the operation of the processes and apparatus of this invention, it ispreferred that when the waste material feedstock is an organic material,it should be as fresh as possible with a high moisture content. In otherwords, such a waste material feedstock should have undergone no, or aslittle as practical, composting, decay, digestion or other bioconversionprior to processing according to this invention. This provides thehighest nutrient value and organic matter content in the final productand is desired where the product produced is a food product, an animalfeed product, a fertilizer or soil builder product or other productwhere nutrient value or organic matter content is important. Thispreferred aspect is efficiently achieved by a preferred design of thesystems of the present invention, which is the modularization of theprocess units in skid-mounted or other form suitable for transport bytruck. This enables the entire system of this invention to be sizedappropriately and placed on-site at various operations and manufacturingfacilities and enables processing of the waste material feedstock fromsuch operations and facilities immediately after it is produced. Thispreferred system for such operations provides additional economic andenvironmental efficiency, because it eliminates the cost andenvironmental impact of transporting any waste material feedstock to adistant location for processing or disposal. Eliminating the necessityof transporting waste material feedstock from one location to anotheralso provides the benefit of biosecurity between facilities, i.e., iteliminates the transport and spread of harmful or undesirable plant andanimal diseases. This design also enables custom or jobber wastematerial feedstock processing where the truck mounted units are easilymoved from one waste material feedstock production or accumulation siteto another, in order to maximize the utilization of the capitalinvestment in the equipment systems employed for carrying out thisinvention. Such portability also enables full utilization of theequipment of this invention, which can be scaled to an appropriate sizefor efficient, economical operation, so it can be used on a part timebasis at each of several different operation or manufacturing locationsin a particular area where a permanent installation at any singlelocation is not needed or is not economically justifiable. The system ofthis invention can also be scaled to appropriate size for an individualoperation or manufacturing location to operate full time to continuallyprocess the waste material feedstock continually produced in thatlocation, so that waste material feedstock stockpile or excess wastematerial feedstock at any time the manufacturing facility is inoperation is minimized.

For use in this invention, it is preferred that the waste materialfeedstock have a high moisture content, such as at least 30% by weightwater, preferably at least 50% and most preferably at least 70%. Thehigh water content facilitates mechanized handling of the raw materialand preparing it for use by blending and mixing for uniformity offeedstock. Typically the waste material feedstock is moved by augers,front end loaders, back hoes, conveyor belts and the like, particularlyin slaughterhouse, farm, forestry, landscape and similar operations.However, in those and other operations the waste material feedstock maybe prepared in the form of a pumpable slurry, where the water content ofthe waste material feedstock may be as high as 90%, 95% or even 98%. Inaddition, the waste material feedstock may be a solution with all solidsdissolved therein, where the solids are precipitated out as the water isevaporated from the feedstock in the processes and systems of thisinvention. The present invention can efficiently and economicallyprocess such high water content waste material feedstocks to not onlyrecover the solids content in the form of a final product, but to alsorecover the process water, which can be recycled for industrial orprocess use, for livestock drinking water, for crop or landscapeirrigation, etc. This invention can handle high water content wastematerial feedstocks efficiently and economically due to the fact thatexcess steam produced in the dryer vessel can be used downstream,upstream or in other nearby operations, such as for preheating wastematerial feedstock, process heat, etc. Instead of holding high watercontent waste material feedstocks in open ponds, as is conventionallydone in many industrial and manufacturing operations, this inventionenables holding the waste material in enclosures or tanks foressentially immediate processing, which eliminates the air pollution,odor and environmental problems associated with open ponds. Thisinvention can be adapted as disclosed herein, to contain and process notonly the water and solids but also the gases produced in a manufacturingoperation. In some cases it may be desirable for economic operationreasons to mechanically separate part of the water from high-watercontent waste materials, e.g., by centrifuges, filters or presses,before processing the waste material in the system of this invention.Such separated water can be recycled for use as disclosed above.

It is recognized that a raw waste material feedstock will typicallycontain other material such as straw, twine, wire, gravel, rocks, juteor plastic bags, etc. Such materials are processible as part of thewaste material feedstock in the present invention without detrimentaleffect, provided the levels of such other materials are not unusuallyhigh. However, it is normally preferred to separate out such materials,particularly rocks, wire and the like, that might damage the dryervessel or downstream processing equipment. Otherwise, it may bedesirable to prepare the waste material feedstock by chopping, grindingor other preparation to comminute items such as twine, bags and the likeinto small pieces so they can be processed into the final productwithout significant interference with the normal operation of theprocesses and apparatus of this invention or with the end use of theproduct. It should be noted that such materials that are either inert orare biodegradable can be contained in the fertilizer product withoutdetrimental effect, which may be particularly desired where it is noteconomically efficient to remove such materials from the waste materialfeedstock or during processing according to this invention. The wastematerial feedstock preparation by grinding, chipping, chopping,crushing, etc., not only will improve the uniformity of the feedstockfor processing, but will also facilitate addition of other materialsinto the feedstock, such as straw, woodchips, yard waste, etc., asreferred to above. In addition the waste material feedstock preparationcan include a washing step, which may be useful in very dry wastematerial, to remove excess salt content or other components that may notbe desired in a final product.

The term “gas turbine” is used herein to mean and include any turbineengine having a compressor turbine stage, a combustion zone and anexhaust turbine stage that is capable of producing exhaust gastemperatures of at least 500° F., preferably at least about 700° F.,more preferably at least about 900° F. and most preferably greater thanabout 1,000° F. Gas turbines are the heat source preferred for use inthis invention because of their efficient operation and high heatoutput. The gas turbine generator is further preferred for use in thisinvention due to the production of energy by the generator, which energycan be utilized or sold to improve the economics of the operation of thesystem of this invention. The generator will typically be an electricgenerator due to the convenience of using and/or selling the electricityproduced. However, the generator can be any other type of energygenerator desired, such as a hydraulic pump or power pack that can drivehydraulic motors on pumps, augers, conveyors and other types ofequipment in the system of this invention or equipment in other nearbyoperations. The heat requirements and the system economics willdetermine whether a gas turbine or gas turbine generator is used. If itis desired to have higher temperature exhaust gases and higher heatoutput from a given smaller size gas turbine, it may be desired to use agas turbine instead of a similar size gas turbine generator. Compared tothe gas turbine, the gas turbine generator further expands and cools theexhaust gases in absorbing energy to drive the generator, where in a gasturbine that energy is contained in higher temperature gases availablefor use in the dryer vessel of this invention. This can be an optionwhen it is economically more important in the practice of this inventionto have small (truckable) high temperature units than to have therevenue stream or economic benefit of the electricity or other energyproduction by the gas turbine.

The gas turbine or gas turbine generator useful in this invention can befueled from any available source with any suitable fuel for theparticular gas turbine and for the process equipment designed accordingto this invention. The preferred and conventional fuels are sweetnatural gas, diesel, kerosene and jet fuel because the gas turbines aredesigned to run most efficiently on good quality fuels of these typesand because of their common availability, particularly at remoteagricultural operations, where the units of this invention are oftenmost efficiently located. However, other fuels that can be used to fuelthe gas turbine include methane, propane, butane, hydrogen and biogasand bioliquid fuels (such as methane, oils, diesel and ethanol). Sincethe system of this invention does not produce a biofuel, the fuel forthe gas turbine used in this invention must be available at the localsite where this invention is utilized. If fuel is not available locally,a fuel such as diesel can be trucked to the site as needed.

Examples of commercially available gas turbines and gas turbinegenerators useful in the present invention include the following (ratedmegawatt (MW) outputs are approximate):

-   -   Rolls Royce Gas Turbine Engines Allison 501-KB5, -KB5S or -KB7        having a standard condition rated output of 3.9 MW    -   European Gas Turbines Tornado having rated output of 7.0 MW    -   Solar Mars 90 having rated output of 9.4 MW and Solar Mars 100        having rated output of 10.7 MW    -   Solar Tarus 60 having rated output of 5.5 MW and Solar Tarus 70        having rated output of 7.5 MW

For a nominal product output capacity of 2.5 metric tons/hr. (2,500kg/hr) a gas turbine generator size of about 4 MW can be used, dependingon the heat insulation and heat recovery efficiencies designed into theoverall system. For small single semitrailer or truck systems, the unitsmay be scaled smaller. For smaller product output systems, such as an0.3 metric ton/hr product output, small gas turbines, such as SolarSaturn 0.8 MW, Solar Spartan 0.2 MW or Capstone 0.5 MW or 0.3 MWgenerators, can be used depending on system efficiencies and requiredheat input ranges. It will be recognized that systems according to thisinvention can also be designed to utilize the exhaust gas heat fromreciprocating engines, such as gasoline or diesel generators.

The dryer vessel employed in this invention can be any type orconfiguration that is suitable for drying the waste material feedstockavailable and that can be adapted for receiving the gas turbine exhaustgases and receiving the waste material feedstock without allowing asignificant amount of outside air to enter the drying chamber in thedryer vessel where the exhaust gases contact the waste materialfeedstock. The objective of the design of the gas turbine exhaustconnection to the dryer vessel for purposes of this invention is topreclude any significant outside air from entering the dryer vessel tohelp prevent significant oxidation of the waste material feedstock. Aspreviously pointed out, this is preferred to preserve the organicmatter, carbonaceous and/or nutrient values present in those types ofwaste material feedstocks, to prevent fires and to provide a safeoperation. As used in this invention it is preferred and expected thatthe turbine will be operated at a conventional ratio of fuel tocombustion air in order to produce the most efficient exhaust gastemperature (EGT) for the dryer vessel and to produce gases entering thedryer vessel that contain a minimum of free oxygen. It will berecognized by those skilled in the art from the disclosure of thisinvention, that alternate sources of hot gases other than a gas turbinecan be used and connected to the dryer vessel, such as the exhaust fromconventional oil or gas burners and reciprocating engines, provided theyare operated at conventional combustion ratio conditions to minimizefree oxygen, or at stoichiometric ratio for no free oxygen, in theexhaust and are connected to the dryer vessel in a fashion thatprecludes significant outside air from entering the dryer vessel inorder to preclude significant oxidation of the feedstock. Of course,such an alternate and additional source of hot gases can optionally beconnected to the dryer vessel according to this invention and be used tosupplement the exhaust gases output of the gas turbine in order toprovide additional heat input capacity for the dryer vessel if neededfor start up, shut down or surge load conditions or for backup in theevent the gas turbine goes off line.

It will be recognized that in some operations of this invention, not alloutside air can be excluded and oxidation of the waste materialfeedstock cannot be completely precluded, primarily because of the airpresent in and entrained in the waste material feedstock, the airdissolved in the moisture present in the waste material feedstock andexcess oxygen that may be present in the turbine exhaust gases duringperiods that stoichiometric ratio of fuel and air is not achieved. Inaddition, in some cases oxygen may be produced or liberated from theorganic or other materials present in the waste material feedstock whenthe thermal treatment and conversion takes place and decomposes orconverts such materials. Therefore, the terms as used herein which referto “preclude introduction of air,” “without significant oxidation,” andthe like, are used in the above operational context and with therecognition and intended meaning that the air or oxygen entering thesystem as part of the waste material feedstock or exhaust gases orproduced in the thermal conversion process is not intended to beprecluded and that the oxidation that may occur as a result of that airentering the system with the waste material feedstock is not intended tobe prevented. However, such a level of oxidation is not consideredsignificant within the scope, context and practice of this invention orthe meanings of those terms as used herein. Similarly, “withoutsignificant pyrolysis” is used herein to mean that not more than aninsignificant portion of the waste material feedstock is pyrolized,e.g., as in U.S. Pat. No. 6,039,774. Pyrolysis products are undesirablein the processes and products of the present invention, and theprocesses and equipment of this invention are operated to achieve thedesired drying of the waste material feedstock and the desiredconversion and destruction of various waste material feedstockcomponents, such as pesticides, prions, organisms, seeds, etc., butoperated to avoid significant oxidation and preferably to avoidsignificant pyrolysis, or at least to minimize oxidation and minimizepyrolysis. Following the disclosures herein, it will be apparent to oneskilled in the art for some applications of this invention, to controlthe exhaust gas temperatures, the contact times and/or residence timesin the dryer vessel, the moisture content of the solids and of the vaporphase in the dryer vessel and other variables in order to process aparticular waste material feedstock to achieve these desired results andto maximize the nutrient value in the final products. In otherapplications of this invention the temperatures, contact times and otheroperating parameters of this invention can be adapted to achieve adesired level or degree of oxidation or pyrolysis, if the properties ofthe final product to be made using the systems of this invention requireoxidation or pyrolysis of the feedstock.

Dry or low moisture content waste material feedstock is likely to havemore air entrained in the interstices among the particles than wet orhigh moisture content waste material feedstock, and elimination of suchentrained air from a dry waste material feedstock before introductioninto the dryer vessel may not normally be economically practical.However, consistent with other operational aspects of this invention, itis often preferable to use high moisture, low air content waste materialfeedstock, and may be preferable to add water to a dry waste materialfeedstock to displace air therefrom before processing in the systems ofthis invention. Minimizing introduction of air and oxygen into the dryervessel is preferred to prevent significant oxidation of the nutrientcomponents of the waste material, as well as other components of thefeedstock, such as straw, dust, etc., that might pose a fire or safetyhazard if excess air or oxygen were present in the dryer vessel.

Exclusion of outside air is also preferred for economic efficiency aswell, because heating excess or outside air along with heating the wastematerial feedstock reduces the efficiency of the process. In someinstances where the waste material feedstock is very low in moisturecontent or too dry for preferred operation of this invention, water canbe added to the feedstock, to the turbine exhaust, to the turbine intakeor to the dryer vessel to raise the moisture level in the dryer vesselto a level for efficient operation and to produce a solids material fromthe dryer vessel with a desired moisture content and desiredself-binding properties. Addition of water to a dry waste materialfeedstock followed by mixing, kneading or pressing, such as in windrowmixing and pressing with a roller, can also serve to displace air fromthe feedstock before being introduced into the dryer vessel. In the caseof very dry waste material feedstocks, water may be considered a processaid added before entry into the dryer vessel.

It will be recognized that the operation of the dryer vessel is normallyto dry or reduce the moisture content of the waste material feedstock,but it is to also achieve the high temperature heating of the wastematerial feedstock to convert or destroy undesired components and toachieve a chemical or thermal alteration in the feedstock to provideproperties desired in the final product. As noted, one aspect of thisinvention is the thermal conversion of the various components of thewaste material feedstock without significant oxidation from the outsideair. Since the specific components of waste material feedstocks arenumerous and varied, it is not clearly understood what specific chemicalreactions may be taking place in the various thermal conversions, andapplicants do not wish to be bound by specific theories or speculationregarding same. However, certain observations have been made, and theunderstanding of the following observations will further enable oneskilled in the art in effectively and efficiently practicing thisinvention.

First is the thermal conversion and destruction of undesirablecomponents, such as organisms, chemicals, etc., as discussed elsewherein this disclosure. Second is the thermal conversion, chemically orphysically, of various components in the waste material feedstock. Forexample, the product produced can be an essentially self-binding solidproduct that can be made into high physical strength pellets, granulesor prills without the addition of binders or similar materials. Whileconventional binders for forming pelletized, granulated or prilled solidproducts can be used in the practice of this invention, it is preferredto operate at thermal treatment temperatures and residence times toproduce a material that is self-binding and can bepelletized/granulated/prilled without added binders. It is believed thatto some extent, when the organic matter in the feedstock is chemicallyaltered and/or thermally converted, similar to being “cooked,” ittransforms ligands, cellulose, starch, carbohydrates, etc., intomaterials that can act as binders in the final product. This provides abinding profile to enable formation of a final product having particlestrengths and free flowing anticaking and nonfriable properties thatmake it useful in conventional dry product handling, transport andapplication equipment. Waste material feedstocks that range from veryhigh to very low proportion of organic matter present can be convertedto self-binding materials that will form good strength pellet, granuleor prill products without additional binders added. Of course,additional binders may be added to enhance the strength properties ofany of the final solid products of this invention, if desired. Third isthe recognition that in some operations of processing a very lowmoisture content waste material feedstock, there may actually not be anysignificant drying taking place, i.e., the moisture content of thefeedstock entering the dryer vessel may be essentially the same as thematerial exiting the dryer vessel, so the dryer vessel is essentiallyacting as an oven. In this case, the important processing taking placeis the thermal treatment or conversion and/or chemical alteration(“cooking”) of at least a portion of the organic matter or othercomponents present in the feedstock.

The types of dryer vessels that can be used in this invention are, forexample, the following:

-   -   Rotary drum with or without internal scrapers, agitation plates        and/or paddles    -   Stationary “porcupine” drum dryer with or without scrapers        and/or agitator plates and/or paddles    -   Triple pass stepped drying cylinder or rotary drum dryer systems        with or without scrapers and/or agitator plates and/or paddles    -   Rotary drum dryer systems with or without steam tubes and with        or without scrapers and/or agitator plates and/or paddles    -   Turbo-dryer or turbulizer systems    -   Conveyor dryer systems with or without scrapers and/or agitator        plates and/or paddles    -   Indirect or direct contact dryer systems with or without        scrapers and/or agitator plates and/or paddles    -   Tray dryers    -   Fluid bed dryers    -   Evaporator systems    -   Baking ovens

Examples of commercially available dryer vessels useful in or that canbe adapted for use in this invention include:

-   -   Scott AST Dryer™ Systems    -   Simon Dryer Ltd.—Drum dryers    -   Wyssmont Turbo Dryer systems    -   Duske Engineering Co., Inc.    -   Energy Unlimited drying systems    -   The Onix Corporation dehydration systems    -   International Technology Systems, Inc. direct or indirect dryer        systems    -   Pulse Drying Systems, Inc.    -   MEC Company dryer systems

Further examples of dryer vessels useful in or that can be adapted foruse in this invention are disclosed in U.S. Pat. No. 5,746,006 to Duskeet al. and U.S. Pat. Nos. 5,570,517 and 6,367,163 to Luker, thedisclosures of which are incorporated herein by reference in theirentirety.

As noted above the “dryer vessel” does not necessarily always functionprimarily as a dryer by removing moisture from the waste materialfeedstock in the system of this invention. The dryer vessel alsofunctions as the thermal treatment/conversion/alteration vessel or ovenin which the waste material feedstock is heated to sufficienttemperatures for sufficient times to produce the desired final materialsand products as disclosed herein. In addition, the dryer vessel need notprovide direct contact of the turbine exhaust gases or other heat sourceand the waste material feedstock, but can provide indirect heating ofthe waste material feedstock to achieve the drying and/or thermaltreatment/conversion/alteration desired according to this invention. Thedryer vessel can be lined with appropriate material to prevent or reducecorrosion, erosion or excessive wear. It will be recognized that thesystems of this invention can be adapted to perform various functions invarious configurations in a particular installation or operation. Forexample, two dryer vessels can be operated in series where a high watercontent feedstock is dried in the first dryer vessel then the outputfrom the first dryer vessel is thermally treated in the second dryervessel to achieve the desired chemical or physical conversion oralteration. In such an arrangement, the exhaust gases can be suppliedfrom a single gas turbine exhaust split between the two dryer vessels,or can be supplied by two separate gas turbines. From this example itcan be seen that the processes, apparatus and systems of this inventioncan be adapted to operate various equipment components in series or inparallel to perform various processing functions desired following theteachings of this invention to achieve the effective and economicoperation thereof.

Another aspect of the dryer vessel adapted for use in this invention isthat the dryer vessel preferably also functions as the silencer for thegas turbine or other engine providing the hot exhaust gases. It is wellknown that gas turbines, (essentially jet aircraft engines), produce ahigh level of noise impact on the nearby environment. Stationary gasturbines used for electric power production or other purposes areusually required by local, state and federal regulations to havesilencers installed to muffle the noise of the exhaust of the gasturbine to acceptable levels. Such silencers have the economicdisadvantages of cost and creating back pressure on the gas turbineexhaust, which reduces the efficiency of the gas turbine operation. Oneadvantage provided by this invention, due to the connection between thegas turbine exhaust and the dryer vessel preferably being closed tooutside air, is that the dryer vessel functions effectively as asilencer for the gas turbine. This is at least in part a result of theinternal configuration construction of the dryer vessel acting incombination with the presence of the high water content waste materialfeedstock, which combination is effective in absorbing and muffling thegas turbine exhaust noise. This is also due to the downstream end of thedryer also being closed to the atmosphere, because the steam and offgases from the dryer vessel are collected for condensation, cleaning,recycling and for heat recovery in the downstream processing in a closedsystem before being vented to the atmosphere. It will be apparent to oneskilled in the art that capability for venting at various points in theprocess and the equipment system may be desirable to accommodatestartup, shutdown, upset or feedstock variability, but will normally beoperated as a closed system having only final product output and cleangas venting. The turbine exhaust can optionally be partially ortemporarily wholly diverted to other downstream units, bypassing thedryer vessel, when needed for supplemental heat in other process unitsor for startup, shut-down or upset.

Another advantage provided by this invention is that the steam and offgases can be pulled from the discharge end of the dryer vessel by anappropriate fan, vent blower, etc., to provide a reduced pressure at theupstream entrance of the dryer vessel, thereby reducing the backpressure on the turbine exhaust. This increases the efficiency ofoperation of the gas turbine and is made possible because the connectionbetween the gas turbine exhaust and the dryer vessel is not open tooutside air. It will be understood that the commercial system design mayinclude a vent or even a conventional silencer connected by tee or otherconfiguration into the connection between the gas turbine exhaust andthe dryer vessel for use during startup, shut down or upset operation,but would not be employed in the normal operating configuration for theprocess and apparatus of this invention as described above. To achievebest efficiency of operation of this invention, it is preferred that theconnection between the gas turbine exhaust and the dryer vessel inlethave no obstructions in order to deliver the exhaust gases to the dryervessel with a minimum of heat and energy loss between the gas turbineand the dryer vessel. It will also be recognized from this disclosure,that the operation of a gas turbine generator will preferably becontrolled for optimal efficiency or economics for the waste materialfeedstock drying, thermal conversion, chemical alteration and otherprocessing needs, which may not be the optimal or best gas turbineoperating conditions for electricity production. The electricityproduction is a cost recovery revenue stream for the system, but theoverall economics of the operation of this invention may be better undergas turbine operating conditions that favor optimum exhaust heat outputfor efficient dryer vessel operation and downstream production ofproducts having desired properties and disfavor electricity production.Determination of such operating conditions for a particular installationof this invention will be apparent to one skilled in the art followingthe teachings herein. Gas turbine control systems of this type aredisclosed in commonly assigned copending U.S. patent application Ser.No.______ (Attorney Docket No. 033976-006) filed on even date herewith,the disclosure of which is incorporated herein by reference in itsentirety.

Another advantage provided by this invention results from the contact ofthe gas turbine exhaust gas with the waste material feedstock in theconfined space of the dryer vessel without significant outside airpresent. The NO_(x) and SO_(x) emissions, and to some extent CO and CO₂emissions, in the gas turbine exhaust are substantially reduced, and insome cases reduced to zero, by absorbing or complexing of the NO_(X) andSO_(X) components into the waste material feedstock, where they remainabsorbed, complexed or fixed in the dried or treated material exitingthe dryer vessel and in the product after processing into granular,pellet or prill or other form. This provides the advantage of bothlowering or eliminating the emissions of NO_(X) and SO_(X) (and CO/CO₂)into the atmosphere and adding the nitrogen, sulfur and carboncomponents to the nutrient value of the product produced by the processand apparatus of this invention.

The operating conditions and procedures for the dryer vessel will beapparent to one skilled in the art following the teachings herein of thedisclosure of this invention. The typical turbine exhaust gastemperature entering the dryer vessel will be in the range of about 500°F. to about 1,500° F., depending on moisture and other content of thewaste material feedstock and the desired condition of the fertilizer orsoil builder material output from the dryer vessel. In smaller systemswith smaller engines, the inlet exhaust gas temperature can be as low asabout 300° F. or about 350° F. A preferred range is from about 600° F.to about 1200° F., and it is more preferred that the inlet temperaturebe at least about 650° F. and most preferably at least about 700° F. Thetemperature and flow rate of the gas entering the dryer vessel willdepend in part on the moisture content and other properties of the wastematerial feedstock. Higher moisture content will obviously generallyrequire higher inlet gas temperatures to reduce the moisture content. Itis believed that an additional efficiency is achieved in the systems ofthe present invention where high moisture content waste materialfeedstock is contacted with high temperature gases. Such contact causesthe formation, sometimes instantly, of superheated steam as the moisturecomes out of the waste material feedstock, then that superheated steamheats and drives the moisture out of adjacent waste material feedstock.It is believed that this mechanism is responsible for quick drying ofthe waste material feedstock to a low moisture content so that theremaining residence time of the waste material feedstock in the dryervessel contributes to the desired thermaltreatment/conversion/alteration or “cooking” thereof according to thisinvention. Some waste material feedstocks may require lower temperaturesbut longer residence time to achieve the conversion or “cooking” neededto produce a product having self-binding or other desired properties.The temperature of the material exiting the dryer vessel will typicallybe in the range of about 150° F. to about 450° F. and preferably betweenabout 200° F. and about 350° F. In some operations, the dryer vesselexit temperature of the material should be at least about 175° F. andpreferably at least about 200° F.

The self-binding properties of the materials and products of thisinvention are one of the important preferred aspects of this invention.While conventional binders and additives can optionally be used toprovide desired physical strength properties of the granules, pellets orprills in desired shapes and forms, it is frequently preferred that theoperating conditions should be those that cook and convert the wastematerial feedstock to produce a self-binding product, such as an animalfeed product, recyclable product, fuel product, etc. Those operatingconditions will depend on the moisture content and the organic mattercontent of the waste material feedstock that is capable of beingconverted to components having binding characteristics. While notunderstood and not being bound by any particular theory, it is believedthat starch, protein, carbohydrate and sugar components are converted toglutenous-like or other materials that can act as binders and that oiland ligand-type components are polymerized to act as binders. In anycase, the operating conditions include temperatures of the exhaustgases, contact time between the waste material feedstock and exhaustgases, temperatures achieved by the feedstock solids, the residence timeof the waste material feedstock solids in the dryer vessel at elevatedtemperatures and other process factors. These conditions will determinethe temperature to which the solids will need to be raised and thelength of time the solids are subjected to the elevated temperatures inorder to produce a self-binding product. Such temperature may not be aconstant temperature for a particular increment of solids but may be atemperature profile rising over a period of time to a maximum, thendescending over a period of time or may descend rapidly if the dryervessel output is quenched at the exit. Optimum conditions to achieve anoptimum self-binding product can be determined for a particular wastematerial feedstock following the disclosure herein.

As used herein the term “converted material” is used to refer to andmeans the dried waste material feedstock which is produced in the dryervessel by reducing the moisture content of the waste material feedstockfrom an existing level to a lower level according to this inventionand/or achieving the chemical alterations and conversions referred toherein. The “converted material” is considered an intermediate productthat is suitable for further processing into a final fertilizer productsuitable for consumer, commercial or industrial use. Typically theconverted material from the dryer vessel will be processed by milling toproduce a powder or meal, followed by granulating, pelletizing orprilling of the powder or meal to produce the final product suitable forconventional handling, packaging and/or transport. The convertedmaterial can also be milled or otherwise powdered and made into a slurryor other liquid or pumpable product that can be recycled or used asintended. Local economics will have an impact on determining the end useto be made of the material produced from the dryer vessel or the finalproduct produced from the system of this invention and whether thematerial from the dryer vessel is subjected to further processing asdiscussed below.

As used herein the term “granule,” “granulating” and the like refer toany granular form of the material or product produced by this invention,including conventional granules, powder, dust, crumbs and the like,produced by conventional granulation processes and equipment, includingcrushing or crumbling previously formed pellets or prills. The term“pellets,” “pelletizing” and the like refer to any pellet form of thematerials or products produced by this invention, including cylindrical,bullet, spherical or other shape, typically made by conventionalpelletizing processes and equipment, such as by extruding a slurry orpaste and cutting, chopping, or breaking the extrudate to the desiredsize. The terms “prills,” “prilling” and the like refer to any prillform of the materials or products produced by this invention made byconventional prilling processes and equipment, including spray towerprocesses, freeze drying processes, etc.

An extrusion pelletizer is one of the preferred process units for use inconnection with or as part of this invention, because it takes advantageof the self-binding properties of the material produced in the dryervessel, and because it can be operated under temperature and pressureconditions that may provide or further contribute to the “cooking” ofthe material to produce the basic and/or enhanced self-bindingproperties of the product of this invention. In a typical operation, thematerial from the dryer vessel is milled, and the powder or meal fromthe milling unit may be mixed with steam or water, for example steam orcondensed water vapor from the dryer vessel, sufficient to form materialthat is extrudable at high pressure and temperature to form pellets orother shapes. The heating and temperatures achieved in the extrusionpellitizer may be from heated screws, dies or drums or may be from theenergy of high pressure compression. In either case the extrudablematerial is heated to a high temperature in the process. It is believedthat for some waste material feedstocks that the high temperature andpressure in the extruder pelletizer may further “cook” or convertcertain components in the material to provide or contribute toadditional or enhanced self-binding properties of the resultingpelletized, granulated or prilled product. Typical operating conditionsfor such an extrusion pelletizer will be an extrudable material havingmoisture content of up to about 20% by weight or higher, depending onthe extruder equipment employed. Extruder temperatures and pressure willbe those normally used in conventional extruder equipment. Otheroperating conditions can obviously be employed depending on the wastematerial feedstock being processed and the desired properties of theformed product. The pellets produced may be dried to reduce the moisturecontent to a level suitable for stable product storage, e.g., about 10%by weight. The moisture removed at this point in the process can berecycled for use in other steps and processes of the systems of thisinvention, as disclosed herein.

The waste material feedstock will typically have a moisture contentbetween about 50% and about 90% by weight, preferably between about 60%and about 80% by weight and most preferably between about 65% and about75% by weight. (Percent by weight, as used herein, is in reference topercent of the component in question based on the total weight of themixture referred to.) Although waste material feedstock of lowermoisture content, for example, as low as about 40% by weight or even 30%by weight can be processed in this invention. The preferred wastematerial feedstock has a moisture content of at least about 50% byweight, more preferably at least about 60% and most preferably at leastabout 70% by weight. When the waste material feedstock has a highmoisture content in this range, processing advantages are achieved fromthe essentially instant production of steam and superheated steam at theinlet of the dryer vessel where the 1,000° F. exhaust gases contact thehigh moisture waste material feedstock at atmospheric or subatmosphericpressure. The steam and superheated steam thus produced contributes tothe drying, cooking and conversion of adjacent or nearby and downstreamparticles of waste material feedstock, which enhances the efficiency ofthe process. It is preferred for operation of the process and apparatusof this invention that the waste material feedstock be mixed and blendedamong batches or different parts (top, bottom, indoor, outdoor, etc.) ofthe same batches to provide a uniformity of waste material feedstockproperties. This preferred preparation enables the production of a moreuniform material from the dryer vessel, and simplifies control of theprocess operations. The temperature of the waste material feedstock willtypically be ambient, i.e., in the range of about 30° F. to about 100°F., but can be lower than 30° F., provided that any frozenagglomerations do not interfere with the feedstock preparation or theoperation of the dryer vessel and feedstock feeder equipment. The wastematerial feedstock may be used at any temperature direct from amanufacturing facility or from a process unit, which may be at anelevated temperature. The economics of the systems of this invention areusually improved if the waste material feedstock is at an elevatedtemperature or is preheated prior to introduction into the dryer vessel.If preheating is used, it preferably is done just before use in thisinvention so composting and bioconversion are kept to a minimum. If suchfeedstock preheating is employed, it may be done in any desired fashion,such as heat exchanger, solar heating, heated conveyers or augers orheated concrete slabs in the staging and feedstock preparation area, andmay be done with heat recovered and recycled from the process systems ofthis invention.

The contact time between the turbine exhaust gases and the wastematerial feedstock will be determined by several variables includingmoisture content of the feedstock, moisture content desired in the dryervessel output material, the chemical alteration/conversion desired,volume and temperature of the exhaust gases entering the dryer vesseland other factors. The contact time will be regulated to provide notonly the drying desired, but also to elevate the particles of wastematerial feedstock solids to sufficiently high temperatures tosufficiently destroy or convert to harmless forms, the undesirablecomponents present in the feedstock, such as organisms, microorganisms,seeds, pesticides, antibiotics, hormones, prions, viruses and the like,when such conversion or destruction is desired, and to produce aself-binding product, when desired. The actual temperature attained bythe particles is not important to determine, so long as the desiredlevels of said component destruction and conversion, the desired levelof self-binding or other desired properties are achieved. The desiredcontact time can be varied and regulated by the dryer vessel volume andsize and by the throughput volumes of the feedstock and exhaust gases.The heat transfer from the exhaust gases to the feedstock, andconsequently the temperature to which the feedstock is heated, willmainly be a function of the mass ratio of exhaust gas to feedstock. Anexample of the dryer vessel operation with a gas turbine generator is aRolls Royce Allison 501-KB5 generator (rated at 3.9 MW) having anexhaust gas output of about 122,000 lb./hr. at 1,000° F. and connectedto a Scott Equipment Company, New Prague, Minn., USA, rotary tubulardryer model AST 8424 having an internal volume of about 26 cubic meters(m³). The waste material feedstock is a slaughterhouse waste materialcomminuted to small particle size and having a moisture content of about70% by weight and a temperature of about 65° F. and is fed to the dryervessel at a rate of about 6,500 kg./hr., which is about 10 m³/hr.,(about 16,200 lb./hr.) to provide an average or nominal residence timeof the solids in the dryer vessel of about 10 to about 18 minutes and aweight ratio of exhaust gases to waste material feedstock of about 7.5.The dryer vessel output is at about 200° F. The weight ratio of exhaustgas to feedstock will generally be between about 15:1 and about 1:1,preferably between about 10:1 and about 3:1 and more preferably betweenabout 8:1 and about 4:1. The heat requirement may call for a ratio of atleast about 20:1 or at least about 25:1 or higher where the feedstock iscold with a very high moisture content and the exhaust gas is not at ahigh or maximum temperature. The exhaust gas flow and the waste materialfeedstock flow through the dryer vessel may be concurrent,countercurrent, single stage, multiple stage, etc., depending on resultsdesired and various system designs and economic considerations.

The output from the dryer vessel comprises steam, water vapor,combustion gases and solids that are dried and/or thermally treated andconverted to desired forms. Typical dryer vessel outlet temperatures ofthe gases and/or solids will normally range from about 200° F. to about350° F., but lower or higher temperatures may be selected and/or desiredfor economic, product quality and/or process efficiency reasons. Theoutlet temperatures can be from at least about 110° F. to at least about5000° F., preferably at least about 180° F. and more preferably at leastabout 200° F. It is generally desired that the solids material exitingthe dryer vessel will generally have a moisture content between about10% and about 15% by weight, but can range from about 5% to about 25% byweight. Again, lower or higher moisture content of the dryer vesseloutput solids may be selected and/or desired for similar reasons. Thesteam, water vapor and combustion gases exiting the dryer vessel willnormally be routed through heat exchangers (for recovery of process heatusable downstream in granulating or pelletizing operations or upstreamin feedstock or turbine intake air preheating), condensers (for recoveryof process water for upstream or downstream use, for agriculturalapplication or for disposal), scrubbers, filters or cyclones (forrecovering solids entrained in gases or liquids and rendering gases andliquids environmentally acceptable for release) and other conventionalprocess equipment.

The solids output from the dryer vessel, referred to herein as convertedmaterial, are typically further processed by milling, granulating,pelletizing, prilling or other processing to produce a final feed, fuel,recycle or other product in the form desired for packaging or bulkdistribution, transport and use. Such milling, granulating, pelletizingor prilling equipment and operations useful in this invention are thosethat are conventional and well-known, since the output from the dryervessel comprises solid and vapor components that lend themselves to suchprocessing. Whatever the product in whatever form, the process, systemand equipment of this invention provide for environmentally andeconomically effective processing of waste material feedstocks to removethem as environmental liabilities and provide products which arecommercially useful, and to eliminate disposal in a municipal sewer orlandfill. This invention can be used to produce a variety of productsand materials from waste material feedstocks, but the preferredmaterials and products are those that have no significant undesirablecomponents remaining that have not been converted or destroyed in theheating, chemically altering and/or drying treatment in the dryer vesselor other operations. The products and materials produced by thisinvention are preferred to be useful feed, fuel, recyclable or otherproducts, but this invention is also useful in producing reduced-volumesolids for disposal in landfill with the advantage of providing solidshaving low levels or no amounts of harmful components to leach out fromthe landfill into surface or ground water.

The products and materials produced by this invention are useful for andinclude blends with other materials, products or chemicals, as may bedesired for particular end uses requiring particular properties orcharacteristics. Such other materials and additives can be added andblended at any appropriate point in the process: blended with the wastematerial feedstock, added to the dryer vessel, added in the processwater at any point, added to the material exiting the dryer vessel,added as part of any milling, granulating or pelletizing processing orsimply mixed with the final product or blended in before bagging orpackaging or at the point of use. For example the final products, whileusually relatively odor free, can be blended with other materials thatcan either provide a pleasant odor or mask any unpleasant odor. Suchmaterials can be synthetic (perfumes) or natural, with natural materialsbeing preferred. Natural, organic materials can include sage, mint,fennel, garlic, rosemary, pine, citrus and similar materials that wouldnot prevent certification as an organic input. Other materials forblending can include iron, minerals, carbon, zeolite, perlite, chemicalfertilizers (urea, ammonium nitrate, etc.), pesticides and othermaterials to adapt the product for specialized use.

The systems of this invention include configurations that can be used toreduce and in some operations essentially eliminate the emission intothe atmosphere of noxious odors and greenhouse gases from manufacturingoperations, from various processing facilities, and from composting ororganic waste material, referred to herein as “emissions gases.”Manufacturing operations are coming under increasing regulation byfederal and state agencies due to increasing pressure from populationareas near the manufacturing operations. The regulation is directed totwo aspects of air quality. The first is noxious odors in emissionsgases, which contain mercaptans and many other organic compounds thathave offensive odors and which are objectionable to residentialcommunities. The second is greenhouse gas emissions that are harmful toair quality. Greenhouse gases include CO₂, CH₄, and N₂O and are usuallyreferred to in terms of CO₂ equivalent effect on the atmosphere. Methane(commonly released from composting waste material stockpiles or lagoons)has a CO₂ equivalent factor of about 23 (as used by the USDOE) whichmeans that 1 kg of CH₄ released into the atmosphere is equivalent to 23kg of CO₂ released. (Some sources give the equivalent factor as about21.) While CH₄ is the main greenhouse gas produced by bioconversion oforganic waste material, CO₂ and NO_(x) gases are also produced. It isparticularly desired to prevent NO_(x) release into the atmosphere,because it is estimated to have a CO₂ equivalent of about 310. Thisinvention can be used, as disclosed herein, to essentially eliminateatmospheric release of emission gases by containing and processing theemission gases, by immediate processing of waste material feedstock toprevent decomposition or bioconversion of organic matter and/orcontaining and processing emissions from decomposition or bioconversionthat takes place before the waste material feedstock can be processed.

The systems of this invention are particularly useful in essentiallyeliminating the release of emission gases from manufacturing operations.In the basic system of this invention, the gas turbine exhaust isconnected to the dryer vessel. To control emission gases produced in amanufacturing operation, the gas turbine air intake is connected to themanufacturing facility ventilation system so that the ventilation airexhausted from the facility is directed into the gas turbine air intakewhere two processes normally will take place. First, the emission gasesare burned along with the regular gas turbine fuel supply, therebyconverting the CH₄ to H₂O and CO₂ and converting the mercaptans andother noxious or acrid compounds to H₂O, CO_(x), NO_(x) and SO_(x).Second, the exhaust gases from the gas turbine are contacted with thewaste material feedstock, where the NO_(x) and SO_(x) and to some extentCO_(x) gases are absorbed into or complexed with the waste materialfeedstock as it is dried and/or thermally treated to form a convertedmaterial, and preferably to form a final product. This aspect of thisinvention prevents the emission gases from entering the atmosphere.

Existing manufacturing facilities that can immediately directly andefficiently utilize this invention for control of emission gases arethose that are normally completely enclosed and ventilated by fresh airinlets and exhaust air outlets, and particularly those that are climatecontrolled by heating and air conditioning. The exhaust air from suchfacilities is directed to the gas turbine combustion air inlet. Inaddition, facilities can be economically enclosed (e.g. by canvas walls)and ventilated by forced air (with or without climate control) tocollect essentially all the emission gases from the manufacturingoperation and directing the exhaust vent air to the gas turbine airintake.

In utilizing this aspect of this invention it will be recognized that itis preferably operated so that all the ventilation air exhausted fromthe manufacturing facility is fed to the gas turbine air intake toprevent release of emission gases to the atmosphere. Any remainingcombustion air needed for the gas turbine will be from ambient airthrough a conventional air filter, although it is preferred that thefacility exhaust vent air also pass through the gas turbine intake airfilter to prevent damage or erosion of turbine components by entraineddust or other particles. The solids collected in the air filter can befed to the dryer vessel or to other process units in the system forincorporation into the final product produced by the systems of thisinvention. Although the methane or other oxidizable gases in theemission gases will not normally constitute a significant portion of thefuel requirements of the system of this invention, it is burned toproduce heat and is not released to the atmosphere. Nevertheless, everykg of emission gas burned reduces the outside gas turbine fuelrequirement by an equivalent kg. This aspect of the invention alsoprovides the benefit of turbine inlet noise control. Similar to thedryer vessel acting as a silencer for the turbine exhaust, having theturbine inlet enclosed and air ducted in a closed system from themanufacturing facility substantially contains and muffles the highfrequency turbine inlet noise.

It will also be recognized that, while the above description is in termsof using a gas turbine, the same utilization of this aspect of thisinvention to control emission gases can be made using whatever heatsource is selected for use in the system. Whether the heat source is agas turbine, gas turbine generator, reciprocating gas or diesel engineor even a conventional oil or gas burner (like 107 in FIG. 1), themanufacturing facility exhaust vent air can be directed to thecombustion air intake so the emission gases are burned and preferably sothe combustion gases are contacted with the waste material feedstock.

As further disclosure and illustration of the processes, systems andequipment of this invention, reference is made to the schematic flowchart of FIG. 1. In the exemplary process illustrated, gas turbinegenerator unit 100 comprises gas turbine 101 and electric generator 102.The gas turbine has air intake filter 104 and fuel feed 103. If desired,optional bypass exhaust silencer 106 can be included for startup,shutdown or upset conditions during those times the gas turbine isrunning but the exhaust gases cannot be directed into the dryer vessel.However, dryer vessel 200 will function as the silencer in the normaloperation of the system of this invention. Alternatively, instead ofsilencer 106, the exhaust gas bypass (see 908 in FIG. 5) around thedryer vessel can be directed to any appropriate downstream unit, such asseparator 208 and/or separator 600, which can provide a temporarysilencer function. This arrangement eliminates the cost of a separatesilencer and the space required for a separate silencer, which is animportant consideration for the portable, truck-mounted systems. The gasturbine 101 exhaust is connected to the dryer vessel 200 by connector105. An optional air inlet (not shown) can be included for dryer vessel200 in connector 105 or elsewhere for purging the dryer vessel or thesystem, for startup or shutdown or for other reasons, particularly wheneither the exhaust gases or the waste material feedstock is not presentin the dryer vessel 200. However, when both are present, any such airinlet is closed and not used in order to substantially precludeintroduction of air into the dryer vessel and to preclude significantoxidation of materials being processed in the dryer vessel 200. Optionalburner 107 can also be included to provide supplemental heat source andcombustion gases for the dryer vessel, which can be provided for inputin connector 105 or elsewhere. The optional supplemental heat source maybe useful during startup, shutdown, process upset, turbine outage or tomaintain desired throughput when a peak load or unusually high watercontent feedstock is encountered.

The waste material feedstock is typically introduced into the system bymechanical means, such as pump, auger or whatever is appropriate for aparticular feedstock. In this illustration and example, a front endloader 201, drops a solid waste feedstock into a rock separator, mixer,chopper unit 202. The feedstock can be further mixed and foreign objectsseparated in screw conveyers 203, 204 then fed to the dryer vessel 200through 215. The feedstock can also be pre-mixed or conditioned fordesired uniformity prior to loading into this system by loader 201,e.g., in storage windrows that can be combined and mixed.

The output from the dryer vessel 200 is transferred by conduits 205, 206to separator 208 where the solids and gases are separated. The gasespass through 209 and blower 210 to the atmosphere via 211 or to otherdownstream processing via 212. Blower 210 can be operated to lower thepressure in separator 208 and in the dryer vessel 200, which will reducethe water boiling point in the dryer vessel and will reduce the waterboiling point in the dryer vessel and will reduce the backpressure onthe turbine exhaust and increase the turbine output and efficiency.Alternatively, blower 210 can be operated to maintain increased pressurein dryer vessel for higher temperature treatment, conversion or“cooking” of the waste material feedstock is desired. The output fromdryer vessel 200 can pass through optional heat exchanger 207 forrecovery of process heat for use downstream or in preheating the wastematerial feedstock or turbine intake air. The solids output fromseparator 208 pass to ball mill or hammer mill 300 via conduit, conveyoror auger 301 and optional mixers and conditioners 302 and 303. Inaddition, recycled solids, such as fines, from recycle loop 305 can bemixed in at 303 via 304 to be combined for feeding to the ball mill orhammer mill 300. The fines and off spec material generated at variouspoints in the system can be collected and recycled via loop 305 andreintroduced into the product processing system at any desired point forfurther processing, such as the milling unit 300 via 304, thepelletizing unit 400 via 404 or even the waste material feedstockpreparation 202, 203, 204 or other points. An important capability ofthe system of this invention is the complete recycle via recycle loop305 of all fines or off spec solids so that they are eventuallyincorporated in the final products. Thus, the system of this inventionprovides 100% conversion of the waste material feedstock solids (exceptfor rocks and other foreign objects that are not processible) into thefinal products and does not produce a solids waste stream that must beotherwise disposed of, such as in a landfill.

The ball mill or hammer mill 300 is used to produce a uniform smallparticle size, short fiber length material called “meal” which issuitable for processing in pelletizer unit 400 to provide a product thathas sufficient hardness and mechanical durability and stability for theconventional processing, packaging and storage normally used for dryproducts. The output of ball mill or hammer mill 300 goes throughseparator 310 where vapors are taken off and sent via 315 to separator600 for recycle of solids via recycle loop 305 and venting of vapors tothe atmosphere via blower 601 and vent 602. Separator 310 takes outfines or material suitable for recycle via recycle loop 305 and passesthe meal to mixer 311. The meal is then sent via 312 to separator 401and either direct to pelletizer 400 via 408 or to holding or surge bin402 via 409 a and 409 b for mixing with other materials, recyclematerials from 404 or additives or for holding in case of processstartup, shutdown or upset. From surge bin 402 the meal is sent throughmixer 403 and either directly to the pelletizer unit 400 via 417 or tomixer 311 via 412 for mixing with fresh meal when desired.

The pellets from pelletizer 400 are passed through heat exchanger, vaporremoval unit 405 and from there sent via 406 and 414 either direct tofinal product cleaning in units 407 and 415 and finished productshipping or storage bin 500 via 416 a, 416 b, 501 and 503, or sent via413 and surge bin 410 to a crumbler or granulator unit 411 then to finalproduct cleaning units 407 and 415. The final product is loaded in truck502 via 501, 503 or via storage bin 500 for transport to market. Thefines and off spec product separated out in final cleaning unit 415 canbe recycled for reprocessing via recycle loop 305. The crumbler orgranulator 411 converts the pellets to smaller particle or granular sizehaving essentially the same hardness and mechanical durability andstability as the pellets. The solids can be transported betweenprocessing units of this invention by conventional augers, elevators,conveyor belts, pneumatic tube conveyors and the like, as appropriatefor the material and for environmental considerations. As is apparent,the system can be designed and configured to produce a material orproduct from dryer vessel 200 (that can be baled for direct use), mealfrom mill unit 300 (that can be bagged for later processing or fordirect use) or a granular product, a pellet product or a prill productfrom 415.

An example of the operation of the system according to this inventioncan be seen from the following table. This example is based on the useof a Rolls Royce Allison 501-KB5 (rated at 3.9 MW) gas turbine generatorand a Scott Equipment Co. dryer model AST 8424 processing slaughterhousewaste material to produce a protein source animal feed product.

Example of System Sized for Nominal 2.5 Metric Tons/Hr Finished Product

Stream No. Component Flow Rate Condition 103 Natural Gas 820 kg/hrAmbient Temp. 104 Combustion Air 48,140 kg/hr Ambient Temp. 105 ExhaustGases 48,960 kg/hr 1,200° F. 215 Waste Material 6,500 kg/hr 70% H₂O/Feedstock Ambient Temp. 200 Residence Time 10-18 min. 301 Dried Material2,730 kg/hr 12% H₂O by wt. 200° F. 312 Meal 2,500 kg/hr 10% H₂O by wt.125° F. 503 Pelletized Animal 2,500 kg/hr 12% H₂O by wt. Feed Product 15° F. above Ambient Temp.

FIG. 2 illustrates one configuration of the system of this invention inthe form of skid-mounted, truck mounted or rail car mounted units thatcan be transported to and operated at desired manufacturing operationsites where waste material feedstock is available on a daily or periodicbasis. The first unit 700 comprises the gas turbine 101 and generator102. The second unit 701 comprises dryer vessel 200 and separator 208.The dryer vessel 200 has waste material feedstock inlet 215 and isconnected to the gas turbine exhaust by connector 105 when stationaryand in operation. The third unit 702 comprises the processing equipmentdesired for a particular operation, such as the ball mill andpelletizer. The product output is conveyed by 501 to storage units 500or to truck 502 for transport to market. Optional equipment can alsoinclude units for bagging and other packaging of the final product forvarious markets.

FIG. 3 is an illustration of the same units as in FIG. 2, but positionedon the operation site in a different configuration. It is apparent thatthe portable, truck-mounted units of this invention are adaptable to avariety of sites that may have limitations on space available.

FIG. 4A is a plan view and FIG. 4B is an elevation view of anotherportable configuration of the system of this invention wherein alloperating units are mounted on a single semitrailer truck 800 a and 800b. Gas turbine unit 100 exhaust is connected to dryer vessel 200 byconnector 105. Dryer vessel 200 has waste material feedstock inlet 215and is connected to separator 208 by conduit 206. Separator 208 isconnected to vapor/air cleaner separator 600 by conduit 209 andseparator 600 vents to the atmosphere by vent 602. The bottom outlet ofseparator 208 is connected via conduit 301 to ball mill unit 300. Theoutlet of ball mill unit 300 is connected via conduit 312 to pelletizerunit 400, which is connected to product cleaning unit 415 by conduit414. Cleaning unit 415 has product outlet 416. Not shown in FIGS. 2, 3and 4 is an optional enclosure for each skid-mounted or truck-mountedunit to enclose the entire unit for weather protection and for noiseattenuation.

FIG. 5 is a schematic process flow chart of some of the optional systemsof this invention. Manufacturing facility enclosure 900 and wastematerial pits 901 are enclosed and ventilated with fresh air 902. Theventilation air 903 from the facility is fed to the gas turbine 101 aspart of the combustion air feed 904 through air filter 104. The wastematerial pits 901 can be within the same enclosure or can be separateholding tanks or lagoons that are enclosed so that all vapors given offby the waste material can be contained and passed to the gas turbine 101along with the facility ventilation air 903 for combustion along withthe conventional gas turbine fuel 103, such as locally available naturalgas. This prevents greenhouse and noxious or acrid gases from themanufacturing operation and the waste material from being released intothe atmosphere, including biogases from any bioconversion that takesplace before the waste material can be processed in the system of thisinvention. Not only does this provide the opportunity for commercial useof this invention to obtain air quality credits for reduced greenhousegas emissions, it also provides manufacturing operations a way to becomeacceptable neighbors with nearby residential areas, because all noxiousand acrid odors from the operation and the waste material can becontained within the system and incorporated in the final product orconverted to components that are not noxious or acrid before venting tothe atmosphere.

The gas turbine generator 101/102 produces electric power 905, which canbe either sold to the local power company 906 or distributed by 907 foruse in the manufacturing operation or the processing units in thesystems of this invention. Some manufacturing operations will find thatthe cost of enclosing an open manufacturing facility and installing andoperating ventilation in order to contain and process all greenhousegases via 903 can be at least partially if not substantially offset byusing the electricity 905 for operation of the ventilation system. Forexample, it may be feasible, or necessary in some instances due togovernmental regulation, to cover a normally open manufacturingoperation with inflatable tents, similar to those used for tenniscourts, to provide economical systems for containing and collecting allemission gases from such an operation, so those gases can be processedvia 903 according to this invention. The economics of each commercialoperation, fuel costs, selling price/purchase price of electricity andcapital cost of equipment will determine whether the electricity is usedinternally in the manufacturing operation, sold to the power company,used in the systems of this invention or used in other nearby operationsor any combination thereof.

The exhaust gases from the gas turbine 101 are passed to dryer vessel200 by a connection 105 that precludes outside air from entering thedryer. As disclosed herein, the system is operated so that the oxidationof the waste material feedstock in the dryer vessel 200 and elsewhere inthe system is minimized and substantially avoided. The dryer vessel 200also serves as silencer for the gas turbine. An optional bypass 908 canbe provided so the exhaust gases can be sent to downstream equipment,such as separators/condensers 208, to silence the gas turbine exhaustwhen the dryer vessel is off line and to clean the exhaust gases beforerelease into the atmosphere during such temporary operation. This bypasseliminates the cost of having a separate silencer to satisfy noiserestrictions on the gas turbine when the dryer vessel is off line andprovides a more compact design for portable or truck mounted units.

Waste material feedstock 215 is fed to the dryer vessel 200 along withthe exhaust gases from connection 105 and any auxiliary heat providedfrom alternate or auxiliary heat source 107. The waste materialfeedstock preferable comes directly from the waste material pits 901 infacility 900 so it is fresh and has little or no time for bioconversion.Other waste material feedstock sources 910 can be used or included inthe system, such as stockpiled waste material or waste material fromother operations that is brought in to be combined or mixed with thewaste material from the immediate facility. As disclosed herein, othergreen waste, organic materials, inorganic materials or additives can becombined with the waste material for processing in the system of thisinvention.

The output from dryer vessel 200 is sent via 205 to theseparators/condensers designed to separate the solids 912 for furtherprocessing downstream, to condense the water vapors as reclaimed water913 and to clean the gases 914 vented to the atmosphere. The reclaimedwater can be used downstream as process water, recycled for use in themanufacturing facility or preparing or conditioning the waste materialfeedstock, used for livestock water or used for crop irrigation. Thesolids output 912 from the separator units 208 is normally furtherprocessed by milling, pelletizing, granulating, bagging, etc. However,the solids 912 can be used as an intermediate to form other types ofproducts. For example, the dry material can be baled, formed intoshapes, slurred for pumping, or can be used alone or in combination withother materials for incineration to utilize the fuel value of thematerial.

In each of the downstream operations, water vapor may be recovered andrecycled to the separators/condensers 208 for reuse. As is apparent, thesystems of this invention are adaptable to various configurations andvarious designs depending on the processing needs and economics ofparticular animal feeding operations. Various conventional heat recoveryand recycle aspects, not shown in FIG. 5, can be designed intocommercial installation of the systems of this invention by usingordinary process engineering design skills, including the fines recycle305 shown in FIG. 1, use of gas/vapor stream 914 for various heatrecovery and pre-heating applications, insertion of binders, additivesand blending materials at various desired points in the system, coolingthe combustion air and/or facility ventilation air, e.g., by waterspray, to increase efficiency and power output of the gas turbines,dewatering very high water content waste material feedstock, etc. Thefinal pelletized, granulated or prilled product 915 can be bagged orshipped bulk for conventional handling, transport and end use.

As will be apparent to one skilled in the art, multiple gas turbines,other engines and/or burners of the same or varying types and sizes canbe manifolded together to feed multiple dryer vessels of the same orvarying types and sizes in a single installation. This can be done tonot only provide increased feedstock processing capacity but also toprovide operation flexibility for processing varying feedstock loads andfor performing equipment maintenance without shutting down theoperation.

While we have illustrated and described various embodiments of thisinvention, these are by way of illustration only and various changes andmodifications may be made within the contemplation of this invention andwithin the scope of the following claims.

1.-14. (canceled)
 15. Apparatus for treating waste material feedstockcomprising: a gas turbine; a dryer vessel receiving exhaust gases fromthe gas turbine through a connection, receiving waste material feedstockand drying or thermally treating the waste material feedstock by directcontact of the exhaust gases and the waste material feedstock to producea converted material, wherein the connection between the gas turbine andthe dryer vessel substantially precludes the introduction of air intothe dryer vessel; and a processing unit receiving the converted materialfrom the dryer vessel and forming same into granular, pellet or prillform.
 16. Apparatus according to claim 15 wherein the gas turbinecomprises a gas turbine generator.
 17. Apparatus according to claim 62wherein the gas turbine comprises a gas turbine generator. 18.-61.(canceled)
 62. Apparatus according to claim 15 wherein the connectionbetween the gas turbine and the dryer vessel directs essentially 100% ofthe gas turbine exhaust into the dryer vessel.